148 HILL BIRDS OF SCOTLAND 



also a curious fact that the cock Grouse has no moult 

 before the nesting season ; it breeds in the plumage 

 it has assumed at the beginning of the winter. The 

 hen, on the other hand, has a complete summer dress 

 before she commences incubation. It has been sug- 

 gested by a well-known investigator that the moult, 

 in the case of the male bird, has been postponed 

 from spring to summer as a result of the attacks of 

 the strongylus worm. After the winter the Grouse are 

 always a more ready prey to disease, and it is possible 

 that the attacks of the parasite and the strain on the 

 cocks during the season of pairing and nesting has 

 necessitated the postponement of the moult till the com- 

 mencement of June. 



There are so many types of Grouse in existence in 

 these Islands that a precise description of their plumage 

 is impossible. Sometimes on the high grounds birds are 

 found with several of the flight feathers white, and this 

 may well be a " throw back " or atavism to the time 

 w^hen the Grouse was plumaged in white during the 

 winter, and when the flight feathers were white through- 

 out the year. The feet and cheeks of high-nesting Grouse, 

 too, are often white. The young, when first hatched, 

 have the crown dark brown, bordered wuth a still darker 

 colour, which extends in a line across the forehead to 

 the base of the bill, and in a wide band down the back 

 of the neck. The upper parts are prettily mottled with 

 several shades of colour. The cheeks and throat are of 

 pale yellow. 



The Red Grouse occasionally crosses with the Black 

 Grouse, and handsome hybrids result. As I mentioned 

 earlier, apparent hybrids between Grouse and Ptarmigan 

 have been obtained, but they have never been entirely 

 above suspicion. 



Though the Grouse is a bird peculiar to Great Britain, 



